U.S. patent number 6,506,217 [Application Number 09/537,281] was granted by the patent office on 2003-01-14 for moldable post-implantation bone filler and method.
This patent grant is currently assigned to Arnett Facial Reconstruction Courses, Inc.. Invention is credited to G. William Arnett.
United States Patent |
6,506,217 |
Arnett |
January 14, 2003 |
**Please see images for:
( Certificate of Correction ) ** |
Moldable post-implantation bone filler and method
Abstract
Methods for correcting defects at bone repair sites are
provided, which use a moldable, post-implantable bone conforming
material. The method includes the steps of preparing a bone
conforming material, shaping the moldable paste, curing the paste
to form a hardened implant, disposing the implant at a repair site,
allowing tissue to overlay the repair site during healing and if
necessary, further molding the implant to the desired contours of
the bony structure being repaired for up to eight weeks after the
surgery by applying pressure to the tissue overlaying the
implant.
Inventors: |
Arnett; G. William (Santa
Barbara, CA) |
Assignee: |
Arnett Facial Reconstruction
Courses, Inc. (Santa Barbara, CA)
|
Family
ID: |
26824981 |
Appl.
No.: |
09/537,281 |
Filed: |
March 28, 2000 |
Current U.S.
Class: |
623/23.61;
128/898; 424/423; 523/115 |
Current CPC
Class: |
A61L
27/12 (20130101); A61L 27/24 (20130101); A61F
2/28 (20130101); A61F 2002/30957 (20130101); A61F
2310/00293 (20130101); A61F 2310/00341 (20130101); A61F
2310/00365 (20130101); A61L 2430/02 (20130101); A61F
2310/00359 (20130101) |
Current International
Class: |
A61L
27/24 (20060101); A61L 27/12 (20060101); A61L
27/00 (20060101); A61F 2/28 (20060101); A61F
2/00 (20060101); A61F 2/30 (20060101); A61F
002/36 () |
Field of
Search: |
;623/23.61,23.62,23.56
;128/898 ;501/1 ;423/308,309,311 ;424/422,423,549 ;514/785,801,802
;523/115 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: McDermott; Corrine
Assistant Examiner: Chattopadhyay; Urmi
Attorney, Agent or Firm: Christie, Parker & Hale,
LLP
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION
This patent application is based on and claims priority of U.S.
Provisional Patent Application Ser. No. 60/126,745 filed on Mar.
29, 1999, which is incorporated by reference herein.
Claims
What is claimed is:
1. A moldable bone conforming material which remains moldable after
being implanted for a period of time, comprising: at least one
apatitic material; at least one fibrous material comprising
microfibrillar collagen; and at least one fluid; wherein the at
least one apatitic material, the at least one fibrous material and
the at least one fluid when mixed together form a moldable paste
which is shaped and cured outside of subject's body into an implant
of a desired size and shape and which is then implanted at a bone
repair site, wherein the implant is reshapeable at a post-operative
bone repair site to achieve an aesthetic shape in a subject.
2. The moldable bone conforming material according to claim 1,
wherein the apatitic material is in the form of a porous solid or
granular particles.
3. The moldable bone conforming material according to claim 1,
wherein the apatitic material is selected from the group consisting
of hydroxyapatite, apatitic cements, cortical bone from human or
animal cadavers, coral, acidic calcium phosphates, neutral calcium
phosphates, fluoroapatite, carbonate apatite, chloroapatite,
physiological bone serum and mixtures thereof.
4. The moldable bone conforming material according to claim 1,
wherein the apatitic material is hydroxyapatite granules ranging in
diameter from 425 to 1000 microns.
5. The moldable bone conforming material according to claim 1,
wherein the fluid is a physiological buffer solution of sodium
chloride.
6. The moldable bone conforming material according to claim 1,
wherein the fluid contains antimicrobial agents.
7. The moldable bone conforming material according to claim 1,
wherein the fluid contains a mixture of Polymixin B sulfate and
Bacitracin.
8. The moldable bone conforming material according to claim 1,
wherein the fluid is selected from the group consisting of a
solution of sodium chloride, sodium citrate, Polymixin B sulfate,
Bacitracin, sterile water, blood serum and mixtures thereof.
9. The moldable bone conforming material according to claim 1,
wherein the apatitic material is hydroxyapatite granules ranging in
diameter from 425 to 1000 microns and the physiological fluid is a
mixture of sodium chloride solution, Polymixin B sulfate and
Bacitracin.
10. A moldable bone conforming material which remains moldable
after being implanted for a period of time, comprising: at least
one apatitic material; at least one fibrous material comprising
microfibrillar collagen; and at least one fluid; wherein the at
least one apatitic material, the at least one fibrous material and
the at least one fluid when mixed together form a moldable paste,
which moldable paste when formed into an implant configuration is
then cured to a hardened state to form a cured implant, which cured
implant is suitable for implantation at a bone repair site, and
which is reshapeable at a post-operative bone repair site to
achieve an aesthetic shape in a subject.
11. The moldable bone conforming material according to claim 10,
wherein the apatitic material is selected from the group consisting
of hydroxyapatite, apatitic cements, cortical bone from human or
animal cadavers, coral, acidic calcium phosphates, neutral calcium
phosphates, fluoroapatite, carbonate apatite, chloroapatite,
physiological bone serum and mixtures thereof.
12. The moldable bone conforming material according to claim 10,
wherein the apatitic material is hydroxyapatite granules ranging in
diameter from 425 to 1000 microns.
13. The moldable bone conforming material according to claim 10,
wherein the fluid is a physiological buffer solution of sodium
chloride.
14. The moldable bone conforming material according to claim 10,
further including antimicrobial agents.
15. The moldable bone conforming material according to claim 10,
wherein curing is affected by at least one of placing the shaped
implant under a heat lamp, in a heated oven, in a dehydration unit,
and in a dessicant.
16. A moldable bone conforming material which remains moldable
after being implanted for a period of time, comprising: at least
one apatitic material comprising hydroxyapatite granules ranging in
diameter from 425 to 1000 microns; at least one fibrous material;
and at least one fluid containing a mixture of Polymixin B sulfate
and Bacitracin; wherein the at least one apatitic material, the at
least one fibrous material and the at least one fluid are mixed
together to form a moldable paste suitable for implantation at a
bone repair site, wherein the moldable paste is capable of being
shaped and cured outside of a subject's body into an implant of a
desired size and shape, wherein the cured implant is remoldable at
a post-operative bone repair site to achieve an aesthetic shape in
a subject.
17. The moldable bone conforming material according to claim 16,
wherein the fibrous material is in the form of collagen.
18. The moldable bone conforming material according to claim 16,
wherein the fibrous material is selected from the group consisting
of microfibrillar collagen, collagen fibrils, fibrin, gelatin,
polysaccharide elastomers, natural rubber, fibrolamellar bone,
cartilage and mixtures thereof.
19. The moldable bone conforming material according to claim 16,
wherein the fluid further comprises a physiological buffer solution
of sodium chloride.
20. The moldable bone conforming material according to claim 16,
wherein the cured moldable paste, once implanted, can be shaped or
reshaped, if necessary, at the post-operative bone repair site to
achieve an aesthetic shape in a subject.
21. A method for correcting bone deficiencies at a bone repair
site, comprising: preparing a bone conforming material which
consists essentially of at least one apatitic material, at least
one fibrous material, and a fluid, which when mixed together form a
moldable paste; shaping the paste to form a desired implant
configuration; curing the implant configuration to sufficiently
harden the implant configuration; disposing the implant
configuration at the bone repair site wherein it will absorb bodily
fluid and become softened; molding the implant configuration
further if necessary to conform the implant configuration to the
bone repair site; closing the bone repair site, and remolding the
implant configuration, after the bone repair site is closed, by
applying pressure to the tissue overlaying the implant
configuration to thereby affect reshaping of the implant
configuration.
22. The method according to claim 21, wherein the step of remolding
of the implant configuration can be carried out after any swelling
and inflammation in the vicinity of the bone repair site has
diminished.
23. The method according to claim 21, wherein the step of remolding
the implant configuration can be carried out for approximately
eight weeks.
24. The method according to claim 21, wherein bodily tissue will
grow into the implant configuration during healing and eventually
replace the implant configuration with tissue.
25. The method according to claim 21, wherein the apatitic material
is in the form of a porous solid or granular particles.
26. The method according to claim 25, wherein the granular
particles are microspherical particles.
27. The method according to claim 21, wherein the apatitic material
is selected from the group consisting of at least one of
hydroxyapatite, apatitic cements, cortical bone from human or
animal cadavers, coral, acidic calcium phosphates, neutral calcium
phosphates, fluoroapatite, carbonate apatite, chloroapatite,
physiological bone serum and mixtures thereof.
28. The method according to claim 21, wherein the apatitic material
is hydroxyapatite granules ranging in diameter from 425 to 1000
microns.
29. The method according to claim 21, wherein the fibrous material
is in the form of collagen.
30. The method according to claim 21, wherein the fibrous material
is selected from by the group consisting of at least one of
microfibrillar collagen, collagen fibrils, fibrin, gelatin,
polysaccharide elastomers, natural rubber, fibrolamellar bone,
cartilage and mixtures thereof.
31. The method according to claim 21, wherein the fibrous material
is microfibrillar collagen.
32. The method according to claim 21, wherein the fluid is a
physiological buffer solution of sodium chloride.
33. The method according to claim 21, wherein the fluid contains
antimicrobial agents.
34. The method according to claim 33, wherein the antimicrobial
agents comprise a mixture of Polymixin B sulfate and
Bacitracin.
35. The method according to claim 21, wherein the fluid is selected
from the group consisting of a solution of at least one of sodium
chloride, sodium citrate, Polymixin B sulfate, Bacitracin, in
water, blood serum and mixtures thereof.
36. The method according to claim 21, wherein the curing step
comprises at least one of placing the shaped implant under a heat
lamp, in a heated oven, in a dehydration unit, under warm/hot air
flow, and in a dessicant.
37. The method according to claim 21, wherein the curing step
comprises placing the shaped implant under a heat lamp until the
implant hardens.
38. The method according to claim 21, for use in maxillo-facial
surgery and facial reconstruction surgery.
39. A method of surgery which permits post-operative reshaping of
an implant at a bone repair site, comprising: exposing a site for
bone repair; preparing a bone conforming material which consists
essentially of at least one apatitic material, at least one fibrous
material, and a fluid, which when mixed together form a moldable
paste; shaping the paste to form a desired implant configuration;
curing the implant configuration to sufficiently harden the implant
configuration; disposing the implant configuration at the bone
repair site; molding the implant configuration, if necessary, to
conform to correct a bone defect or restore a shape to a bone at
the bone repair site; closing the bone repair site; and remolding
the implant after the surgery, if necessary, by applying pressure
to the overlaying tissue to modify the shape of the implant
configuration, wherein the step of remolding the implant
configuration after the surgery can be accomplished without the
need for anesthetics and can be carried out for approximately eight
weeks after the surgery.
40. The surgical method according to claim 39, wherein the curing
step comprises at least one of placing the implant configuration
under a heat lamp, in a heated oven, in a dehydration unit, under
warm/hot air flow, and in a dessicant.
41. The surgical method according to claim 39, wherein the curing
step comprises placing the implant configuration under a heat lamp
until the implant hardens.
42. The method of surgery according to claim 39, wherein the bone
repair site and body member upon which the surgery is performed is
the face.
43. The method of surgery according to claim 39, wherein the bone
repair site and body member upon which the surgery performed is the
cheekbone.
44. A method for correcting defects in a bony structure comprising:
preparing a bone conforming material which consists essentially of
at least one apatitic material, at least one fibrous material, and
a fluid, which when mixed together form a moldable paste; shaping
the paste to form an implant having a desired shape; curing the
implant to sufficiently harden the implant; placing the implant at
a bone repair site; molding the implant, if necessary, to correct
the bone defect at the bone repair site; closing the bone repair
site; allowing tissue to grow into and overlay the bone repair site
during healing; and remolding the implant, if necessary, by
applying direct pressure to the overlaying tissue to modify the
shape of the implant, wherein the step of remolding the implant can
be accomplished without the need for anesthetics and can be carried
out for approximately eight weeks after application to the bone
repair site.
Description
FIELD OF THE INVENTION
The invention relates to the field of biocompatible bone fillers
and bone conforming materials, and more particularly to a bone
filler and bone conforming agent that can be shaped into an implant
that remains moldable for some time after being implanted in the
body, and a method for using same.
BACKGROUND OF THE INVENTION
The invention is directed to moldable, post-implantation bone
fillers and bone conforming materials that can be formed into an
implant that remains moldable for some time after being implanted
in the body and a method for using the same. During various
surgical procedures, including but not limited to orthognathic
surgeries (surgeries of the jaw and related areas), the surgeon
will often identify depressions and other deformities in the shape
and contour of various bone structures. Indeed, in the field of
facial surgeries, one common reason to carry out surgical
procedures is to make aesthetic and/or functional improvements to
the face. Many times these surgeries require changing the size,
shape, and/or position of underlying bone structure (e.g.
shortening, lengthening, or widening the jaw, augmenting the chin,
etc). Because the underlying bone structure of interest (which is
covered with muscle, fat, skin and other tissues) has a great
influence in determining the exterior contours and appearance of
the body, the ability to easily correct defects and deficiencies in
the post-operative bone structure would be very helpful.
Presently, there are several methods surgeons employ to accomplish
this, including using implants made of silicone, various metals
(such as stainless steel and other materials), hydroxyapatite and
other material. There are sometimes infection problems associated
with implants made of materials that are not completely
biocompatible, such as silicone implants. Hydroxyapatite, Ca.sub.10
(PO.sub.4).sub.6 (OH).sub.2, is similar in property to coral, which
is remarkably close in chemical composition and structure to human
bone. In fact, human bone will grow in to the porous structure of
the implant material and can sometimes even entirely replace the
implanted hydroxyapatite. Other common implant materials include
highly processed bone (from animal or cadaver sources, U.S. Pat.
No. 5,501,706), calcium phosphate cements (U.S. Pat. No.
5,697,981), physiological serums containing hydroxyapatite (U.S.
Pat. No. 5,591,232) and sintered apatite bodies and composites
(U.S. Pat. No. 4,503,157).
Hydroxyapatite is typically provided in the form of microspherical
particles that can be implanted to a site that needs augmentation,
for example, by injection via a syringe-like device. Since the
microspheres are like small ball bearings, they tend to drift, move
or "flow" away from the implantation site after being implanted.
Thus, little control can be exercised over the results. Eventually,
the hydroxyapatite microspheres will stabilize (although as
explained above, not always where the surgeon wants them to be
concentrated). In other cases, hydroxyapatite is provided in solid
blocks that can be machined in to a particular shape, and then
inserted in the desired location adjacent to the bone undergoing
repair, replacement or modification. The solid block sources must
be shaped to fit the specific requirements of the repaired,
replaced or modified bone and are not easily fabricated to conform
to the desired bone shape. Typically, such solid blocks of pure
hydroxyapatite are appropriate for use in expanding jaws and the
like where a solid structure without any moldability is
desired.
While calcium phosphate cements are known that harden in-situ or
that harden and then are shaped in to a pre-formed object useful in
bone repair, there remains a need for a moldable, post-implantable
bone filler and bone conforming material and a method for using
such a bone filler and bone conforming material.
SUMMARY OF THE INVENTION
The invention provides a moldable, post-implantable bone conforming
material and a method for using the bone filler. The bone
conforming material comprises an apatite material and a fibrous
material, such as fibrous proteins (e.g. collagen) mixed with
enough physiological fluid added to form a paste. The bone filler
and the method of using the bone material permits a surgeon to form
implants of desired shapes and sizes outside of the body, implant
the bone conforming material against the bone, close the surgical
site, and continue to be able to adjust or modify the contours of
the patient body in the areas with the bone conforming material for
a period of time by applying pressure to the skin, muscle, and
other tissue overlaying the bone conforming material implant to
thereby mold or shape the implanted bone conforming material. The
time period during which the bone conforming material can continue
to be molded is about eight weeks or longer.
There are tremendous advantages to the bone conforming material of
the present invention. First, a surgeon can mix together a moldable
bone conforming material and pre-shape the bone conforming material
into a desired shape prior to implantation. The surgeon will then
dry the molded bone conforming material, thereby curing it to a
hardened shape and state, preferably by placing it under a heat
lamp, in a heated oven, in a dehydration unit under warm/hot air
flow or a dessicant, or by other suitable curing means. In its
hardened state, it retains its shape and state. It is also possible
to rely on air drying solely, which takes considerably more time,
as compared to drying using a heating unit. After the hardened
implant is positioned in a desired place in the body against a bone
structure, it becomes saturated with blood and other physiological
fluids and softens somewhat like a hardened sponge softens when
saturated. In its softened state, it can be molded further at the
implantation site to more closely conform to the bone and continue
being shaped as required. However, even when it is saturated and
softens, it will not crumble or break up, and remains moldable.
After the surgery, the surgeon will close the surgery site over the
implant. The surgical site will remain inflamed and swollen for
some time, generally for at least several days to several weeks.
For this reason, it is not always apparent to the doctor at the
time of implantation how best to shape the bone conforming material
to the bone. The ability to mold the bone conforming material,
after the swelling has gone down, allows the surgeon to carry out
further shaping of the bone conforming material to achieve improved
aesthetic results. In addition, pre-curing the bone conforming
material prevents the inherent drift of bone material associated
with microspherical bone conforming material materials and
methods.
DETAILED DESCRIPTION OF THE INVENTION
The bone conforming material of the present invention comprises an
apatite, such as hydroxyapatite and a fibrous protein (e.g.
collagen) with enough of a physiological fluid (e.g. saline
solution) added to form a paste. The inventor has successfully used
a source of porous hydroxyapatite, known as INTERPORE 200.RTM. from
Nobel Biocare USA, of Yorba Linda, Calif. INTERPORE 200.RTM.
comprises hydroxyapatite granules that range, in nominal diameter,
from about 425 to 1000 microns. Other satisfactory apatitic
materials for the purposes of the present invention would include
cortical bone powder, acidic or neutralized calcium phosphates,
apatitic cements formed by neutralizing acidic calcium phosphates,
bone powder from human or animal cadavers, powdered coral,
fluoroapatite, carbonate apatite, chloroapatite, physiological bone
serum and mixtures thereof. The inventor has incorporated a source
of fibrous proteins in the form of collagen, known as AVITENE.RTM.
microfibrillar collagen (offered by C.R. Bard, Inc., of Woburn,
Mass.). AVITENE.RTM. microfibrillar collagen (hereinafter referred
to simply as "AVITENE.RTM.") is sold for use as a 100% active form
of collagen (derived from cowhide) hemostate that potentiates the
body's natural clotting mechanism and helps prevent post-operative
bleeding. One contraindication of AVITENE.RTM. is that since it
fills porosities of cancellous bone, the AVITENE.RTM. should not be
used in areas where methylmethacrylate adhesives are to be used.
Other satisfactory fibrous materials for purposes of the present
invention would include collagen fibrils (Type I-III), fibrin,
gelatin, fibrolamellar bone, cartilage, polysaccharide elastomers,
natural rubber and mixtures thereof.
In the present invention, the inventor uses AVITENE.RTM. as a
binding agent to hold together and give shape and form to the
hydroxyapatite when mixed together with the physiological fluid to
thereby prevent it from dissolving and melting out of the
implantation site. Hydroxyapatite and AVITENE.RTM. microfibrillar
collagen are mixed with a saline solution, for example, to afford a
paste or clay-like moldable mixture that remains moldable for an
extended time period, yet retains its shape before complete
hardening. Other suitable physiological fluids for purposes of the
invention would include any physiologically buffered solutions,
namely sodium citrate, phosphate buffers such as TRIS, Polymixin B
sulfate, sterile water, Bacitracin or any other suitable
antimicrobial agents, blood serum, blood plasma and mixtures
thereof. For biocompatability, the inventor has used saline to
moisten the mixture of hydroxyapatite and AVITENE.RTM., but
purified water or physiological fluids could also probably be used
as well. Although in the preferred embodiment, hydroxyapatite is
used with AVITENE.RTM., other apatitic materials might be used in
lieu of hydroxyapatite and other fibrous proteins or other
materials might be used to replace the AVITENE.RTM..
The paste or clay is shaped into a desired implant configuration
(such as a sphere, a boule, a tennis racket, flattened ovals, a
paddle, etc.), and is placed under a heat lamp to drive away excess
liquid and cure the implant. The inventor has used a 65 watt heat
lamp placed close to the shaped implant. Other methods can be used
to drive away excess moisture and cure the mixture, such as placing
the shaped mixture in a heated vacuum chamber, drying oven, or
other suitable drying means. In attempts to eliminate the step of
first hardening the molded implant before it is implanted into the
body, the results were not as optimal. The unhardened implant, when
infused with blood, became very soggy and would not hold a desired
shape. When the surgical site was closed, the pressure of the
tissue would tend to flatten out the implant. When dried, the
implant is basically a mineralized solid, yet retains microscopic
pores. The implant is then placed at the surgery site on the bone
where a defect is to be corrected and/or the bone is to be
augmented. Since the surgical site is seldom completely dry and
free from bodily fluids (namely blood and lymphatic fluid), the
implant will absorb blood and other physiological fluids, and once
more become pliable, much as a dry sponge becomes pliable when
moistened. If the site is too dry, the surgeon can allow blood and
other bodily fluids to infuse the surgical site. However, even when
it is saturated and softens, the implant will resist crumbling and
will break up, and remains moldable. The surgeon can then further
mold the implant to better fit the implant against the bone and as
required for the particular application. For example, cheek bones
can be made as described above, and can be further shaped and
conformed once placed against the bone. The implant will adhere to
the bone very well, and will resist slippage and movement, yet can
be molded by the application of direct pressure to it to conform
exactly to the bone.
After the surgery is complete, the surgical site will be closed
using standard surgical procedures, and healing in the overlaying
tissue will begin to take place. Once the swelling has diminished,
the doctor can, by applying pressure to the site, continue to mold
the bone conforming material and influence the perceived shape of
the underlying bony and implant structure. For example, if the
augmented cheek bone is too angular or pronounced, the surgeon can
flatten or round it as desired. Thus, by making adjustments to the
underlying implant and bony structure, the doctor has the
opportunity to make fine adjustments to contours of the overlying
soft tissue. During this period, the patient must avoid pressure
applied to the part of the body with the bone conforming material
(i.e. the patient must sleep on a soft pillow and avoid contact
sports). As stated above, after about eight weeks, the bone
conforming material will become fully cured and the shaped implant
becomes completely hardened, after which time it will no longer be
capable of being molded further. The inventor anticipates that the
curing time might be varied by changing the materials used in the
implant. Eventually, bone will grow into the porous structure of
the implanted bone conforming material through bone remodeling
processes, then with time partially or completely replace the bone
conforming material.
EXAMPLE 1
Forming the Implant Material
Five cc (5.4 gm) of INTERPORE 200.RTM. porous hydroxyapatite is
placed in a dry plastic bowl. Five cc of a sodium chloride solution
(0.9% sodium chloride in distilled water) are added (optionally
including Polymyxin B Sulfate--500,000 units and
Bacitracian--50,000 units, or other known antimicrobial agents to
control possible infection). The mixture is stirred until all of
the hydroxyapatite is moistened to form a paste. Small amounts of
AVITENE.RTM. are added to the moistened hydroxyapatite, with
complete mixing after each addition. A sufficient amount of
AVITENE.RTM. is added until the mixture will hold together (usually
about 1.0 gm depending upon room temperature and humidity) and
subsequently is formed and shaped to the desired implant shape
depending on the requirements.
The shaped mixture is then placed under a lamp (e.g. a 65 watt heat
goose neck lamp placed about 3 to 4 inches away from the shaped
mixture) for between 15 minutes and 1.5 hours, or until the shaped
mixture is hardened. The hardening or curing time varies depending
upon the size and the shape of the implant being dried and hardened
and the distance between the shaped implant and the lamp. In
practice, heating the mixture longer than 1.5 hours does not harm
the mixture. To increase the drying and hardening time, the lamp
can be brought closer to the shaped implant.
EXAMPLE 2
Implanting the Hardened Implant
After the implant is hardened and cooled down, the surgeon places
it against exposed bone. For example, for cheek bone augmentation,
the hardened implant will be placed in the vicinity of the
deficient prominence of the cheek bone with the overlying tissue
removed to expose the bone. The hardened implant will almost
immediately soak up blood and lymphatic fluids. When moistened with
bodily fluids, the implant will once more become pliable, and can
be shaped further to closely conform to the bony structure and/or
to assume the desired shape (e.g. cheek bone contour). Although the
moistened implant becomes pliable and moldable, unlike plain
hydroxyapatite particles, which tend to disperse from the
implantation site (since nothing keeps them in place), the implant
of the invention will remain in place and retain its shape absent
pressure being applied to the implant. Presently available solid
preformed blocks of pure hydroxyapatite are not moldable at all
even when moistened, and once implanted, the surgeon cannot make
fine, post-operative adjustments. As noted above, even when the
implant is saturated and becomes softened, it will not crumble or
break up, and remains moldable. Furthermore, since the material of
the implant closely adheres to the bone, unlike implants
constructed of silicone and other materials, the implant does not
need to be mechanically attached with sutures, staples, screws, or
otherwise.
EXAMPLE 3
Post Implantation Molding of the Implant
After the surgical site is closed and swelling has receded, the
implant remains moldable for about eight weeks or longer, after
which time the implant will be become completely cured and will no
longer be moldable. Prior to becoming completely cured, the surgeon
can continue to affect changes to the shape of the implant by
applying mechanical pressure to tissue in the vicinity of (e.g.
overlaying) the implant to shape it further. Since the implant will
retain its shape absent pressure being applied, changes to the
shape of the implant will impart changes to the overall appearance
contours of the soft tissue overlying and in the vicinity of the
implant. Eventually, bone and/or connective tissue (e.g., in the
form of osteoblasts) will grow into the implant. After a time, the
implant will be partially or completely replaced with bone tissue,
without changing the overall size and shape of the implant.
The foregoing description is not intended to represent the only
form of the invention in regard to the details of this construction
and manner of operation. In fact, it will be evidence to one
skilled in the art that modifications and variations may be made
without departing from the spirit and scope of the invention.
Although specific terms have been employed, they are intended in a
general and descriptive sense only and not for the purpose of
limitation.
* * * * *